Sensitivity Analysis of Thermo-Mechanical Energy Pile Response Based on Dimensionless Form of Analytical Solutions-Paper

Paper

Pdf Summary

The study reformulates previously developed analytical solutions for the thermally and mechanically induced displacement, strain, and stress of energy piles into dimensionless form. This makes it easier to identify the parameters governing pile response and compare piles of different sizes and materials.<br /><br />The analysis considers end-bearing, fully floating, and semi-floating piles. It assumes one-dimensional behavior, uniform temperature change along the pile, thermoelastic pile material, and reversible interaction between the pile and surrounding soil. The key parameters are ratios of soil stiffness to pile stiffness, pile length-to-diameter ratio, and pile diameter; the semi-floating case also depends on stiffness at the pile tip.<br /><br />Results show that the largest normalized thermal displacements and stresses occur in end-bearing piles, the smallest in fully floating piles, and intermediate values in semi-floating piles. Across all pile types, maximum normalized thermal displacement decreases as the soil-to-pile stiffness ratio and length-to-diameter ratio increase. Maximum normalized thermal stress increases with both ratios. For semi-floating piles, the thermal null point—the location of zero thermal displacement—moves toward the pile midpoint as stiffness and length-to-diameter ratio increase.<br /><br />The dimensionless solutions and trends provide a streamlined basis for understanding energy-pile response and supporting design.

Keywords

energy piles

dimensionless analysis

thermally induced displacement

mechanically induced stress

thermoelastic behavior

soil-to-pile stiffness ratio

pile length-to-diameter ratio

end-bearing piles

fully floating piles

semi-floating piles